We address the problem of pollution attacks in coding-based distributed storage systems. In a pollution attack, the adversary maliciously alters some of the stored encoded packets, which results in the incorrect decoding of a large part of the original data upon retrieval. We propose algorithms to detect and recover from such attacks. In contrast to existing approaches to solve this problem, our approach is not based on adding cryptographic checksums or signatures to the encoded packets, and it does not introduce any additional redundancy to the system. The results of our analysis show that our proposed algorithms are suitable for practical systems, especially in wireless sensor networks.

Abstract Wireless mesh networking allows network operators and service providers to offer nearly ubiquitous broadband access at a low cost to customers. In this paper, we focus on QoS‐aware mesh networks operated by multiple operators in a cooperative manner. In particular, we identify the general security requirements of such networks and we give an overview on the available design options for a security architecture aiming at satisfying those requirements. More specifically, we consider the problems of mesh client authentication and access control, protection of wireless communications, securing the routing, key management, and intrusion and misbehavior detection and recovery. Our aim is to structure this rich problem domain and to prepare the grounds for the design of a practically usable security architecture. Copyright © 2008 John Wiley & Sons, Ltd.

We address the problem of pollution attacks in coding based distributed storage systems proposed for wireless sensor networks. In a pollution attack, the adversary maliciously alters some of the stored encoded packets, which results in the incorrect decoding of a large part of the original data upon retrieval. We propose algorithms to detect and recover from such attacks. In contrast to existing approaches to solve this problem, our approach is not based on adding cryptographic checksums or signatures to the encoded packets. We believe that our proposed algorithms are suitable in practical systems.

In this paper, we present a flexible and mathematically rigorous modeling framework for analyzing the security of sensor network routing protocols. Then, we demonstrate the usage of this framework by formally proving that INSENS (Intrusion-Tolerant Routing in Wireless Sensor Networks), which is a secure sensor network routing protocol proposed in the literature independently of our work, can be proven to be secure in our model.

In this paper we consider the problem of resilient data aggregation, namely, when aggregation has to be performed on a compromised sample. We present a statistical framework that is designed to mitigate the effects of an attacker who is able to alter the values of the measured parameters of the environment around some of the sensor nodes. Our proposed framework takes advantage of the naturally existing correlation between the sample elements, which is very rarely considered in other sensor network related papers. The algorithms presented are to be applied without assumption on the sensor network's sampling distribution or on the behaviour of the attacker. The effectiveness of the algorithms is formally evaluated.

We propose a novel authentication scheme that ensures privacy of the provers. Our scheme is based on symmetric-key cryptography, and therefore, it is well-suited to resource constrained applications in large scale environments. A typical example for such an application is an RFID system, where the provers are low-cost RFID tags, and the number of the tags can potentially be very large. We analyze the proposed scheme and show that it is superior to the well-known key-tree based approach for private authentication both in terms of privacy and efficiency.

In this paper, we consider the application of delay-tolerant networks to personal wireless communications. In these networks, selfish nodes can exploit the services provided by other nodes by downloading messages that interest them, but refusing to store and distribute messages for the benefit of other nodes. We propose a mechanism to discourage selfish behavior based on the principles of barter. We develop a game-theoretic model in which we show that the proposed approach indeed stimulates cooperation of the nodes. In addition, the results show that the individually most beneficial behavior leads to the social optimum of the system.

Routing is one of the most basic networking functions in mobile ad hoc networks. Hence, an adversary can easily paralyze the operation of the network by attacking the routing protocol. This has been realized by many researchers and several "secure” routing protocols have been proposed for ad hoc networks. However, the security of those protocols has mainly been analyzed by informal means only. In this paper, we argue that flaws in ad hoc routing protocols can be very subtle, and we advocate a more systematic way of analysis. We propose a mathematical framework in which security can be precisely defined and routing protocols for mobile ad hoc networks can be proved to be secure in a rigorous manner. Our framework is tailored for on-demand source routing protocols, but the general principles are applicable to other types of protocols too. Our approach is based on the simulation paradigm, which has already been used extensively for the analysis of key establishment protocols, but, to the best of our knowledge, it has not been applied in the context of ad hoc routing so far. We also propose a new on-demand source routing protocol, called endairA, and we demonstrate the use of our framework by proving that it is secure in our model.

Human users need trusted computers when they want to generate digital signatures. In many applications, in particular, if the users are mobile, they need to carry their trusted computers with themselves. Smart cards are easy to use, easy to carry, and relatively difficult to tamper with, but they do not have a user interface; therefore, the user still needs a terminal for authorizing the card to produce digital signatures. If the terminal is malicious, it can mislead the user and obtain a digital signature on an arbitrary document. In order to mitigate this problem, we propose a solution based on conditional signatures. More specifically, we propose a framework for the controlled revocation of unintended digital signatures. We also propose a solution with a special emphasis on privacy issues.

A new code construction is given for slow frequency-hopping multiple-access channels. The construction is based on the cyclic concatenation of special subcodes of two Reed-Solomon codes.>

Constructions of protocol sequences for multiple-access collision channel without feedback are given. These constructions are the extensions of those described by A, Gyorfi, and Massey (see ibid., vol.38, p. 940, May 1992). If the basic code in their constructions, a Reed-Solomon code, is replaced by a BCH code then the resulting protocol sequences have the feature that, for a given sum rate, the ratio of the total user population to the block length becomes much larger.>

The commenter takes issue with certain aspects of the above-named work (see ibid., vol.37, p.834, 1989) by Salehi and Brackett. He notes that when the time delays are constant between synchronous sources, bit error probability is a misleading performance measure. He argues that the measure analyzed in the above-named work shows the probability of availability of the channel instead.>

Code acquisition for a frequency-hopping code-division multiple-access system using Reed-Solomon coding is investigated. The one-coincidence codes which minimize the user interference are shown to be well suited for initial synchronization but are less appropriate for regaining synchronism during transmission. A modified code construction is proposed, which has good capability of both startup and resynchronization.